meson: Add glib_valgrind_suppressions variable to glib pkg-config file

Various projects are running tests under valgrind, and they are using
the GLib suppresions to avoid false-positive results.

While this is stored in a well-known path for some years, and easy to
figure out from the GLib prefix, it's better to expose it through a
proper pkgconfig variable so that it's easy to get it from any build
system.

glib/meson.build

@@ -441,9 +441,14 @@ pkg.generate(libglib,
   subdirs : ['glib-2.0'],
   extra_cflags : ['-I${libdir}/glib-2.0/include'] + win32_cflags,
   variables : ['bindir=' + join_paths('${prefix}', get_option('bindir')),
+               'datadir=' + join_paths('${prefix}', get_option('datadir')),
                'glib_genmarshal=' + join_paths('${bindir}', 'glib-genmarshal'),
                'gobject_query=' + join_paths('${bindir}', 'gobject-query'),
-               'glib_mkenums=' + join_paths('${bindir}', 'glib-mkenums')],
+               'glib_mkenums=' + join_paths('${bindir}', 'glib-mkenums'),
+               'glib_valgrind_suppressions=' + join_paths('${datadir}',
+                 valgrind_suppression_file_install_subdir,
+                 fs.name(valgrind_suppression_file)),
+  ],
   version : glib_version,
   install_dir : glib_pkgconfigreldir,
   filebase : 'glib-2.0',

meson.build

@@ -9,6 +9,8 @@ project('glib', 'c',
   ]
 )
 
+fs = import('fs')
+
 cc = meson.get_compiler('c')
 c_standards = {}
 
@@ -175,9 +177,10 @@ add_test_setup('unstable_tests',
 
 # Allow the tests to be easily run under valgrind using --setup=valgrind
 valgrind = find_program('valgrind', required: false)
-if valgrind.found()
-  suppression_file = files('tools' / 'glib.supp')
+valgrind_suppression_file = files('tools' / 'glib.supp')[0]
+valgrind_suppression_file_install_subdir = 'glib-2.0' / 'valgrind'
 
+if valgrind.found()
   add_test_setup('valgrind',
     exclude_suites: [ 'no-valgrind', 'flaky' ],
     exe_wrapper: [
@@ -191,7 +194,7 @@ if valgrind.found()
       '--show-leak-kinds=definite,possible',
       '--show-error-list=yes',
       '--suppressions=@0@'.format(meson.project_source_root() /
-        '@0@'.format(suppression_file[0])),
+        '@0@'.format(valgrind_suppression_file)),
     ],
     env: common_test_env,
     timeout_multiplier: 20,

tools/meson.build

@@ -17,8 +17,8 @@ endif
 if host_system != 'windows'
   # Install Valgrind suppression file (except on Windows,
   # as Valgrind is currently not supported on Windows)
-  install_data('glib.supp',
-    install_dir : get_option('datadir') / 'glib-2.0' / 'valgrind',
+  install_data(fs.name(valgrind_suppression_file),
+    install_dir : get_option('datadir') / valgrind_suppression_file_install_subdir,
     install_tag : 'devel',
   )
 endif